Temperature control system for frequency determining elements



Nov; 10, 1931. G. P. WALKER 1,831,151

TEMPERATURE CONTROL SYSTEM FOR FREQUENCY DETERHINING ELEMENTS Filed Apr-i1 18, 1929 s sneets-sneet 1 ATTORNEY NOV-10, 1931 G. P. WALKER 1,831,151

TEMPERATURE CONTROL SYSTEM FOR' FREQUENCY DETERMINING ELEMENTS Filed April 18, 1929 s sheets-sheet 2 INVENTOR.

544g/ 5. galega/0,

BY -w-mm A TTORNEY Nov. 10, 1931. v G P, WALKER 1,831,151

TEMPERATURE .ONTROL SYSTEM FOR FREQUENCxr DETERMINING- ELEMENTS Filed April 18, 1929 5 Sheets-Sheet 5 7' cI n /0 INVENTOR. Sw?? 5, lf/aww,

ATTORNY V'Bey Y Patented' Nov. 10, 19.31.

UNITED STA TES '.PATENT* oFFyIcE emr r. wams., orwasnnrcviioia msrmcm or commu Application med April 18,

My invention relates broadly to temperature control apparatus and more particularly to temperature control apparatus employed for maintaining the temperature of frequencontrol devices used in high frequency signaling systems ata substantially constant predetermined value.

One of the objects of my invention is to provide a housing for frequency controlling devices employed in high frequency systems wherein the frequency controlling devices may be maintained at substantially constant temperature.

Another object of my inventionis to proll vide a housing for maintaining at substantially constant temperature frequency controlling devices employed at maximum power output in high frequenc signaling systems. Still another object o my invention is to provide a housing for electromechanical vibrators in which the electromechanical vibrator is so disposed with respect to the heated circulating medium in the housing that it will be maintained ata substantially uniform mean temperature throughout widetemperature variations.

A further object of my invention is to provide an arrangement for maintaining electro-l mechanical vibrators at substantially constant temperature wherein the housing for the electromechanical vibrator is located adjacent a baiile plate member, which is maintained at a mean temperature, for exposing the electromechanical vibrator to the eilects of the circulating medium passing on both sides of the baille plate member;

A still further object of my invention is -to provide an arrangement for maintaining the temperature of an electromechanical vibrator substantially constant wherein the 'electromechanical vibrator is positioned with respect to a heating unit in such a manner that it is practically unafected by the rate.

of change of the' temperature gradient of the medium. external to the electromechanical vibrator.

Another object of my invention is to provide a container for keeping electromechanical 4vibrators at a substantially uniform 5g ltemperature throughout large variations of 192s. .serial No. 356,281.

ambient temperature, wherein a baille plate is provided for`l guiding vthe circulation of the heating medium about the electromechanical vibrator. so that different surfaces of the electromechanical vibrator casing are successively l A exposed 4to the heating effects of the circulating medium andthe mean temperature of the circulating medium is caused to affect the electromechanical vibrator. j

Other and further objects of my invention will be more fully understood from the'following s ecification and the annexed claims.

Accor ing to my invention the temperature of electromechanical vibrators is maintined at a substantially constant value throughout large variations in climatic conditions by positioning an electromechanical vibrator in a container having walls made up of layers of heat insulating or heat retaining material of a cellular structure, and providing a balile plate in the container so positioned adjacent the electromechanical vibrator device that the device is exposed during operation only to the effects of an optimum mean temperature. A heating unit is positioned within the container for heating the gaseous or liquid medium therein. The heating unit does not necessarily need to be positioned within the container but may be supported on the outside thereof or it may be supported in a compartment on a wall of the container. A fan, driven by an electric motor or similar driving means, isemployed to agitate the gaseous or liquid medium inside of the container and cause the heated medium to come in contact with the objects inside of the container whereby equilization of the temperature of the objectsI is more readily obtained. The circulating medium is directed along one side of the baille plate against irst one p0rtion of a housing surrounding the electromechanical vibratorand then in returning to the heating unit the medium is directed against the other portion of the housin The baille plate is positioned with an edge adjacent 4 to the heating unit and with the edge extending along sides of the electromechanical vibrator housing. 'The baille plate, being of a relatively good heat conducting material, such ascopper or aluminum, is maintained at sub- 1 i stantially equal temperature throughout its mass.

The temperature of the medium within the container decreases as it is caused to move farther and farther away from the heating unit. Likewise the temperature of the circulating mediumcontinues Vto decrease as the medium is returning to the heating unit. It is one object of my invention to so dispose the electromechanical vibrator holder in the container, that the magnitude of the coolin of the circulating medium in the course o its traversing the distance from the heating unit to the electromechanical vibrator holder will be the same as the magnitude of the cooling of the circulating medium in its course from the electromechanical vibrator holder to the heating unit. The electromechanical vibrator and its holder is thus kept at a predetermined mean temperature irrespective of the changes in the temperature of large magnitude takin place on the exterior of the container.

veferring briefly to the drawings, Figure 1 illustrates the preferred embodiment of my invention; Fig. 2 illustrates a sectional view along the line 2-2 'of Fig. 1 Fig. '3 is a detail view of the electromechanical vibrator hous-y ing; Fig. 4 is a cross-sectional view along the line 4-4 of Fig. 3; and Fig. 5 shows a series of curves illustrating the theory of operation of my invention. i

In Fig. 1 of the drawings, reference numeral 1 designates a container having walls 2 and '3 of cellulose fiber composition or similar material having a cellular structure. Spacers 4 are employed between the walls 2 and 3 to support these walls in spaced relation in order to rovide a; dead air space between the Walls. cover 5 composed of walls 6 and 7 held together by spacer strips 8 which are disposed along the periphery of the wall 7, is provided on the container 1. A small casl ing 10 having walls 11, 13 and 15 of heat conducting material, such as copper or aluminum, and walls 1'2 and 14 of heat insulating material, such as, cellulose ber composition or similar material having a cellular structure, alternately disposed between the walls 11, 13 and 15, is supported in the container 1 by members 16 and 17 which are also of heat insulating material. A box 18, havin walls of copper or other highly heat con uctive material, is mounted on small supports of heat insulating material within the casing 10. A thermometer 19 is supported against a surface of the box 18 by a socket member 20 which is attached to the box 18. A baffle plate 21 is supported within the container between the casing 10 and the heating unit 22. The baille plate extends preferably on three sides of the casing 10 and is fitted directly against the exterior walls of the casing, as is illustrated in Fig. 2 of the drawings. The heating unit 22 is supported b the member 23 adjacent the end of the ba e plate 21 remote fromthe end adjacent the casing 10. A thermostat 24, preferably of the mercury expansion type, is supported by the members 25, 26 and 27, which are of material, in a position such that the mercury body thereof is substantially one half above and one half below a continuation of the 'upper horizontal plane of the baille late 21.

An auxiliary baffle plate 21a is emp oyed to facilitate the circulation of the medium 1n the container. Baiile plates similar to 21a supply 35 so that the current flowing throughv the heating unit may be varied at will. A relay 34 which is connected to the source of supply 33, the resistance 33a and the contacts offrelay 31, is controlled in operation by the thermostat 24. When the circuit is closed through the thermostat 24, through the action of heat transmitted from the heating unit 22, the relay 31 is energized by current from the source of supply 32 and the resist-- ance 33a is connected across the winding of the relay 34. The current flowing through the relay 34 is decreased in value whereupon connections between the heater unit and the source 35 are rearranged and the current through heating unit is also decreased. The temperature within the container 1 is thus maintained substantially at a predetermined value through the control `of the heating .unit circuits by the thermostat.

In Fig. '3 a detail view of the box structure 18, which is positioned inside of the casing 10 is illustrated. A holder 37 foran heat insulating- A fan 28, actuated by the motorl electromechanical vibrator element is positioned within the box 18 upon supporting members 41 which are of insulating material.' An electromechanical vibrator 44, such as a piezo electric crys al is positioned upon a preferably metallic base of the holder 37 and beneath the contactL plate 43. Connections 39 and 39a are provided between the base of the holder 37 and the contact plate 43. Bushings 40 and 40a are provided in openings in a wall of the box 18 for the entrance of connections 39 and 39a.

The operation of the temperature control apparatus of my invention may be more readily understood from the curves illustrated in Fig. 5 of the drawings. In Fig. 5 the teml perature gradient for conditions of opera-l tion encountered in a relatively warm room and those encountered in a relatively cold room are illustrated by the dotted and the solid curves. The relative positions of the casing 10, thethermostat 24, the heater 22` and the bale plate 21 in the container 1 are shown the same as in Fig. 1.

Under conditions prevailing in a relative- 1y cold room the mobile medium, such as the gaseous or liquid substance in the container 1 must be heated to a` tem erature corre- 'spending-to the point b of t e dotted curve.

of Fig. 5 in order that a certain predetermined temperature is obtained at the thermostat 24.

When the stystem of my invention is operated under conditions prevailing in a relatively warm room the mobile medium within the container 1 must be heated to a temperature corres onding to the point a of the solid curve of Eig. 5 in orderthat the same predetermined temperature may be obtained at the thermostat 24 as was'obtained under the conditions in the relativel cold room.

The temperature of the mo ile medium in its movement. from the thermos'at to the heater,vdescreases to the values c and d un-I der conditions of operation obtained in relatively warm and relatively cold rooms, respectivel It is therefore seen that by positioning t e casing 10 in certain locations with respect to the baiile plate that the interior of the casing will .be maintained at a predetermined mean v,temperature substantially equal to that ofthe thermostat since the variation in the temperature of the portions e and f of the casing 10, encountered in shift- -ing from conditions prevailing in a warm room to those prevailing in a cold room will neutralize themselves and the same mean temperature will be obtained under the different conditions.

It is to be understood that while I have described my invention in certain of its preferred embodiments that I do not desire to be limited to those s cific embodiments eX- cept as defined by t e appended claims since i combination of a' container having walls ofV heat retaining material, a bafile plate posi-V -my invention may be used equally well with various types of frequency controlling and stabilizing devices, such' as tuning forks and magnetostrictionv devices, and is not necessarily confiedto the temperature piezo electric crystal devices.

4What I claim as new and desire tosecure by fietters Patent of the United States is as fol ows:

1. In apparatus of the class described the tioned in said container for guiding the circulation of a mobile heat absorbing vmedium over a predetermined course within said container, means associated with said container for heating said mobile heat absorbing medium, and means for'supporting an' electromechanical vibrator adjacent 'to' said baille plate in such manner'that said electromechanical vibrator is exposed to the effects of a plurality of lcurrents of said medium simultaneously,

control of each of said currents* being of a different teinperature. s

2. In apparatus -of tli'e class described the Y combination of a' container having walls of heat retaining material, means for heating a mobile medium within said container, a baille plate positioned in said container for guiding the circulation of said heated mobile medium therein, means for supporting an electromechanical vibrator adjacent to said baille late for maintaining said. electromechanica vibrator at substantiall uniformtemperature,

and a thermostat positioned adjacent to said ergizing circuits of said heating means, a`

second container having alternate walls of heat retaining and heat conducting material, and means for supporti an electromechanical vibrator within sai second container, said second container being adjacent to the edge of said baille plate adjacent to'said thermostat.- l

4. In apparatus of the class described the combination of a. container, means within said container for heating a mobile medium therein, means operatively associated with said heatin means for maintaining the tem.

perature Within said container substantially uniform, a baille plate located within said container, and a second container of heat resisting material positioned within said `first mentioned containerand extendin above and below said baille plate'whereb t e interior of said second container wil be maintained substantially at a predetermined mean temperature throu hout wide temperature" variations, and an e ectromechanical vibrator positioned within said second container.

5. In apparatus of the class described the iis combination of a container, means associated with said container for heating a mobile med ium therein, a thermostat operatively con-g nected with said means, means positioned in` said container for accelerating. the circulation of said mobile medium therein, a baille plate' positioned in said container for guiding the circulation of said medium, and supportin f means for an electromechanical vibrator, sai su poi'tin means being e osed to the circul3ation o said mobile medium on both sides of said ba-ile plate simultaneousl 6. In apparatus of the class described the Y combination of a container having walls of Afibrous heat retainingv material, a heating .1M`

unit positioned in said container, a. thermostat operatively connected with said heating unit, a bailie plate located in said container for guiding the circulation of gaseous medium therein, and a second container for sup" 'porting an electromechanical Vibrator, said v second container being positioned in a notch in said baffle plate whereby the surfaces of said second container are exposed to the effects of said gaseous medium on both sides of said baille plate.

y GUY P. WALKER.. 

